The present invention relates to a rotating tool, in particular a drill, milling cutter, countersink, deburrer or such like cutting tool, consisting of a working part to be driven in rotation about an axis of rotation and designed, in particular, for cutting machining and of an axially adjoining clamping shank for insertion into a clamping chuck of a drive machine, the clamping shank having, on its outer circumference, a number n≧2 of clamping surfaces for supporting a clamping jaw of the clamping chuck in each case.
In tools of this type, in particular in twist drills and the like, it is known, in the first place, to design the clamping shank cylindrically, that is to say with a circular cross section. This makes very firm clamping of the associated clamping chuck necessary, in order to avoid slipping of the tool, along with the adverse consequences, such as the formation of scores and chips on the circumferential surface of the shank. If clamping is not sufficiently firm, in practice, there is very often slipping of the tool in the clamping chuck.
It is therefore also known, in the case of specific tools, to provide the initially cylindrical shank with secant-like clamping surfaces, thus resulting, in the case of a three-jaw chuck, in what may be referred to as a three-surface driver shank. However, since the clamping surfaces are very narrow in the circumferential direction (the ratio to the remaining cylindrical surfaces being about 1:2 to 1:3), it is very difficult, in the clamping operation, to hit upon the clamping surfaces accurately with the clamping jaws. The cylindrical surfaces are therefore often still hit upon, with the result that the same disadvantages as in the case of completely cylindrical clamping shanks arise. Moreover, even with this type of clamping shank, very firm clamping is still necessary in order to avoid undesirable release during machining.